In general, sound is transferred to auditory nerves of a human body through three ways such as air conduction, bone conduction, and skin conduction, and a human body detects sound using the above.
Among the above, sound conduction by air conduction is a way to transfer sound through general air. That is, vibration of air which is made by a speaker vibrates eardrum and a human body (or a user) senses sound. Sound conduction by bone conduction indicates that a bone conduction transducer converts a sound signal to vibration, and sound is delivered through the bone of a human body (or a user) so that a user can detect sound. In this case, it is necessary that a bone conduction transducer is attached to a part which is closer to the ear with appropriately level of pressure, or a structure to which a bone conduction transducer is attached is installed in the skull through surgical operation. Sound conduction by skin conduction is a way to deliver sound through vibration of external skin of earhole. That is, by delivering a signal of the bone conduction transducer to skin of earhole, a human body (or a user) senses sound. For efficient sound transfer, an ear phone, a head phone, a hearing aid, and a Bluetooth which transfers information or sound wireless within short distance are used.
As to a general earphone, a solid material which is bigger than the earhole is inserted and fixed to tragus and anti-tragus or inside the earhole, and there is an open type and a canal type (see the shape of the ear of FIG. 1)
An open type indicates that a circular-shape earphone is inserted into tragus and anti-tragus. The tragus and anti-tragus are cartilage tissue which plays a role of a support base of an earphone, and they do not endure external small force, and therefore, there is a problem in that the earphone is well come off. In addition, a canal-type earphone has a shape of a straight line or “” shape. In order to fix the earphone on the earhole, a part which enters the earhole is covered with a silicon cap to fix an earphone attached through elasticity of the silicon cap and tragus (and anti-tragus). In the similar manner as the foregoing, an earphone can come off easily, or a user may feel inconvenience due to the silicon cap which fills earholes tightly. As earholes are tightly covered and is not ventilated well, and thus, there are problems that, when a user wears an earphone for a longer time or in the summer, inside the earphone can be damp, and due to excessive pressure, a user may feel pain on his/her hears and eardrum may have a problem.
In addition, in order to deliver sound through the bone, i.e., a signal of the bone conduction transducer is transmitted to the bone and be delivered the auditory nerves, a headphone type, a canal type, or the like has been developed. Among the above, a headphone type is inconvenient when a headphone is worn, and as a bone conduction transducer is away from the earhole which is a position having the best sound delivery efficiency and is in contact with temple located at a front part of earhole, efficiency decreases. In case of a canal type, it gives pressure on the earhole, and a silicon cap part fills the earhole too tightly, and a user may be uncomfortable. Since a silicon cap enters the earhole and is fixed there, and an entire of the earbud set vibrates, and a silicon vibrates by the vibration of the earbud set and delivers vibration, there is a large loss of kinetic energy, and accuracy in a signal falls, thus failing to deliver clear sound quality.
In this regard, provided is an earbud set, a hearing aid, and an earphone using the earbud set which is stably provided in the ears, and even after being worn, the earbud set enables earholes to be ventilated, and a user can hear external sound, and thus, safety accident can be prevented. In addition, in spite of vigorous motion, the present invention is not easily separated, and the present invention has good sound transmission efficiency.